This invention relates to water systems and in particular to municipal and rural water systems having mains which dead-end at various parts of the system. The invention relates particularly to a novel system of flushing hydrants for use in such water systems and to valve assemblies and top stocks for use in the system of flushing hydrants. It also relates to a simplified system for sampling water quality.
Maintaining and monitoring water quality is becoming increasingly important to most water companies. In the United States, for example, the Safe Drinking Water Act amendments of 1986 have caused many water companies to pay very close attention to the quality of water they are providing to their customers. Also, these new regulations require more sampling of the water from points out in the distribution system. These samples are taken on a regular basis and then tested.
Maintaining water quality can sometimes be difficult, especially on a dead-end water main. Water which is located at a dead-end water main becomes stagnant. It loses its chlorine and develops a bad taste and odor; it can also lose its clear appearance and become dark and cloudy. When this happens, or when a break occurs in the main which allows contamination such as bacteria, mud and rocks into the main, the water company sends a crew out to "flush" the water main, by opening a device at the end of the main. Commonly, the device at the end of the main is a flushing hydrant or a blow-off.
A traditional flushing hydrant is a factory-made device installed strictly for the purpose of maintaining water quality. FIG. 1 shows a typical prior art flushing hydrant FH attached to a water main M. The flushing hydrant FH includes a shoe S containing a main valve, a vertical barrel VB containing a valve actuating rod, and a hydrant H permanently attached to the vertical barrel. The hydrant H includes an outlet O and a control nut C for opening the main valve.
A flushing hydrant differs in several respects from a fire hydrant. A fire hydrant is designed with the single purpose of producing maximum possible water flow to fight a fire; it is usually situated in-line with a water main. A flushing hydrant provides means for flushing stale water from a main end. A flushing hydrant is smaller and less expensive than a fire hydrant. A fire hydrant requires a four-inch valve or larger, whereas a flushing hydrant uses a one-inch to three-inch valve, preferably a 1.5"-2.5" valve. A fire hydrant must be available for use in the shortest possible time; a flushing hydrant need not be so easily or quickly operated. An example of a commercially available flushing hydrant is the Eclipse No. 2 post hydrant sold by the John C. Kupferle Foundry Company of St. Louis, Mo.
A blow-off is usually an assembly of factory-made parts, including a buried valve and various sections of piping. Lazenby, U.S. Pat. No. 4,756,479 illustrates a blow-off. FIG. 2 shows a typical prior art blow off BO. The blow off BO includes a ball valve BV attached between a main M and a vertical barrel or pipe BV' having an outlet O' at its upper end. The ball valve BV is controlled by a control C, accessible through a removable lid at ground level.
Although the individual parts of a blow-off are generally less expensive than a flushing hydrant, the blow-off must be assembled in the field, at considerable additional cost and with a considerably greater risk of improper installation.
Flushing hydrants and blow-offs are subject to a number of problems. Water theft, especially in rural areas, is a major problem for most water purveyors; a flushing hydrant or a blow-off is an easy target. Traffic and farm implements tend to hit flushing hydrants and blow-offs because they are sometimes hidden by weeds and brush. This tends to damage both the vehicle and the device. Even if the hydrants or blow-offs survive the collision, the installation is usually damaged and leaks occur. This requires excavating and re-installation of the hydrant or blow-off. In freezing climates, it is important for a hydrant to drain its barrel to a level below the frost-line; when a freeze comes, no water is in the barrel to freeze. During the construction process and in case of a main break, small debris may be left in water mains. This debris will then be flushed out of the water main when put under water pressure. It is important that the debris pass through the main valve and out of the hydrant. Moreover, such debris may be caught in the hydrant valve and damage the valve when it is forced shut.
The sampling requirements for a modern water supply system dictate taking samples from various points in the system on a regular schedule. However, provision of a self-draining feature makes the hydrant subject to incursions of ground water into the hydrant, thereby making the hydrant unsuitable for sampling water quality. Taking samples at other points in the system, however, may be complicated by lockouts from public and private buildings, freezing, and vandalism. Therefore, the John C. Kupferle Foundry Company has introduced its Eclipse No. 88 sampling station, which provides a locked, vandal-resistant access point for taking water samples. This station is described in Waterworld News, July/August, 1990. Such a sampling station, however, requires an additional installation, and it is generally checked by a different crew from the crew which periodically opens flushing hydrants in the system.